Rhodamine-WT and LiCl were compared for their suitability as hydraulic tracers in wetlands. Using outdoor mesocosms, we found lithium to be more conservative than rhodamine-WT when initial concentrations were 4.9 to 64 μg/L for rhodamine-WT and 28–516 μg/L for Li (1:6 to 1:8 (wt/wt) ratio of rhodamine-WT to Li ). At higher initial concentrations (i.e., 100 μg/L for rhodamine-WT and 1000 μg/L for Li ), both tracers returned more than 95% of the injected amount in submerged aquatic vegetation-dominated mesocosms; rhodamine-WT was returned at only 74–75% in cattail-dominated mesocosms. Batch studies using different sediment substrates exposed to direct sunlight and shade indicated that Li was less affected by adsorption and microbial processes than was rhodamine-WT at low initial tracer concentrations of each (4.9 and 19.4 μg/L for rhodamine-WT and 28 and 106 μg/L for Li ). Both rhodamine-WT and Li desorb back to the water column in small amounts. The extent of adsorption losses by rhodamine-WT depended on the organic matter content of the sediment and the extent of photolysis. Even though rhodamine-WT was not as stable as LiCl at initial concentrations less than 60 μg/L, the reduction in the recoveries did not affect the accuracy of key hydraulic parameters (hydraulic retention time, dispersion, tanks-in-series, and wetland dispersion numbers) derived from the method of moments analysis as long as a discernible concentration-time response still existed. This is because the tracer losses were approximately zero-order and irreversible.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 25 • No. 1